Re: [Qemu-devel] [RFC PATCH] vfio: add fixup for broken PCI devices

[Alex Williamson]

On Fri, 2012-05-25 at 17:35 +1000, Alexey Kardashevskiy wrote:
> Some adapters (like NEC PCI USB controller) do not flush their config
> on a sioftware reset and remember DMA config, etc.
> 
> If we use such an adapter with QEMU, then crash QEMU (stop it with
> ctrl-A ctrl-X), and try to use it in QEMU again, it may start working
> immediately with previous config when pci_enable_device() is called
> on that PCI function.
> 
> To eliminate such effect, some quirk should be called. The proposed
> pci_fixup_final does its job well for mentioned NEC PCI USB but not
> sure if it is 100% correct.
> 
> Signed-off-by: Alexey Kardashevskiy <address@hidden>
> ---
>  drivers/vfio/pci/vfio_pci.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index 1e5315c..6e7c12d 100644
> --- a/drivers/vfio/pci/vfio_pci.c
> +++ b/drivers/vfio/pci/vfio_pci.c
> @@ -88,6 +88,8 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev)
>  {
>       int bar;
>  
> +     pci_fixup_device(pci_fixup_final, vdev->pdev);
> +
>       pci_disable_device(vdev->pdev);
>  
>       vfio_pci_set_irqs_ioctl(vdev, VFIO_IRQ_SET_DATA_NONE |

Sorry, just taking a look at this again.  Do you have any idea what
fixup it is that makes it work?  Calling a fixup at this point seems
rather odd.  I suspect the problem is that vfio is only calling
pci_load_and_free_saved_state if pci_reset_function reports that it
worked.  kvm device assignment doesn't do that and I'm not sure why I
did that.  If you unconditionally call pci_load_and_free_saved_state a
bit further down in this function, does it solve the problem?  Thanks,

Alex